Sound reproducer and record.



S. G. PORTER. SOUND REPRODUOER AND. RECORD.

APPLICATION FILED MAY 13, 1911 1,012,910. Patented Dec.26,1911.

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STEPHEN C. PORTER, OF MARTINSVILLE, NEW JERSEY, ASSIGNOR 0F ONE-HALF WALTER H. MILLER, OF ORANGE, NEVJ JERSEY.

SOUND REPRODUCER AND RECORD.

Specification of Letters Patent.

Patented Dec. 26,1911.

Application filed May 13, 1911. Serial No. 626,994.

To all whom it may concern:

Be it known that I, STEPHEN C. ion'rnn, a citizen of the Unit d States, and a residentof Martinsville, Somerset county, State of New Jersey, have invented certain new and useful Improvements in Sound Repro- .ducers and Records, of which the following is a description, 7

My invention relates to sound reproducing devices and records, and particularly to records having a continuous record groove formed thereon of the laterally undulating type and the needle or stylus which tracks the said record groove and co-acts therewith to reproduce the sound recorded. in such records, as commonly made, the groove is in the form of a spiral upon the surface of a reco'rd disk or tablet, the groove being of uniform depth throughout its length, or of slightly increasing depth from beginning to end. The reproduction of sound from a record of this character is effected by the lateral movement of the stylus, as it. follows the lateral undulations of the groove. The stylus or needle which tracks such a groove conical point which roughly fits within the record groove, when it is first positioned therein. When the record is rotated the point of this stylus is worn away and blunted by contact with the record surface, after the record has progressed a short distance, so that it fits within the record groove closely. At the end. of the reproduction the needle has generally been worn to such an extent that it must. be thrown away, and a new needle substituted before the reproducer is used again. The wear of a needle of the character referred to is sufficient to cause the same to accurately fit within the record groove after probably only a fraction of one revolution of the record, and the tracking of the needle is theoretically correct at this )ointat which the needle completely fits the groove. The wear of the needle, however, continues as the record is rotated which causes the tracking of the needle and the reproduction of the record. to become more and more imperfect from this point to the end of the reproduction. This is so,-

to descend, so that the thicker portion of the needle descends to the level of the upis usually formed of soft steel, and has a of the needle causes the latter,

per surface of the record. That is, the diameter of that portion of the cone which is at the level of the upper surface of the record at the end of the reproduction is greater than the diameter of that portion of the cone which is in line with the upper surface of the record at the beginning of the reproduction, because of the wearing away of the apex or point of the cone upon the bottom of the record groove. As the record material is relatively hard and abrasive, and the width of the groove remains the same, this results in the undercutting of the needle by the record and the formation of shoulders upon the needle, which shoulders rest upon the surface of the record and therefore support the needle. I have verified this conclusion by examination, under the microscope, of used reproducing needles. From this point to the end of the reproduction, the point and adjacent sides of the needle continuing to wear, the needle fits more and more loosely in the groove resulting in an imperfect reproduction. I overcome this difliculty by the production of a record in which the record grooveis of decreasing depth from beginning to end to compensate for the wear of the needle. Preferably the decrease in depth of the groove is gradual and progressive from be ginning to end, although obviously the advantage of my invention might be attained at least in part if the decrease in depth of the groove from beginning to end is not exactly uniform. The varying depth of the groove does not affect the reproduction in the type of record referred to, as the reproduction is determined entirely by the lateral movement of the needle. As the needle wears away, the bearing surface for the lower end of the same continually rises so that the portions of the conical surface of' the needle upon which otherwise shoulders would be formed to support the needle, are continually rising, and the point. and conical sides of the needle continue to accurately fit within and perfectly track the groove. The means by which such a record may be produced is not material to the present invention which is concerned only with the record as an article of manufacture, and with the combination between such arecord and a reproducing stylus or needle, formed of soft steel or other material which is relatively soft in comparison with sapphire and other hard stylus materials which are not adapted to wear to fit within the groove of a record formed of compositions of which commercial disk sound records are made. It may be said, however, that a master record is made in any desired manner, having a record of decreasing depth, preferably of uniformly decreasing depth, cut or otherwise formed thereon, a matrix is made from this record from which commercial duplicate records, having grooves of a correspondingly decreasing depth, may be formed by presslng orotli'erwise, as desired. In the formation of the master record, the cutting or recording stylus may be gradually and uniformly raised during its travel, or the pressure which forces the cutting point into the record material maybegradually 'decreased during the making of the record, or as stated, a"groove of the desired character may be formed in other ways. For purposes of illustration one method and means of recording in the desired manner;- upon the master record will be illustrated and described. f

In order that a clearer understanding of my invention may be had, attention is hereby directed to the accompanying drawings, forming part of this specification, in which-- i Figure 1 represents a cross section through a portion of a record disk showing a reproducing stylus or needle in contact with the record groove of the same, the needle being shown in several positions, and the needle and record being greatly enlarged for the purposes of illustration. The record formed as illustrated and the combination of the same with the stylus shown, illustrates one embodiment of my invention; Fig. 2 represents in enlarged cross section a reproducing needle co-acting with a record groove of the common type, showing the formation of shoulders upon the needle above the record surface; and Fig. 3 represents in enlarged cross section the same needle tracking the same groove as that shown. in Fig. 2, at a point in the reproduction of the record, subsequent to the point in the reproduction represented by Fig. 2. Fig. 4. represents in side elevation and vertical cross section, one form of apparatus for forming the desired record groove upon a master record.

In the drawings the sound record disk or tablet 1 is provided with a record groove 2, which, as illustrated,.is of greatest depth at its beginning, adjacent to the periphery 3 of the record, the depth decreasing preferably progressively to the end of the record groove adjacent to the center hole 4 of the Y record. I have shown the groove as of a conical cross section slightly rounded at the bottom, although my invention is not limited to this specific form of groove. Tracking the record and co' a'cting therewith to reneedle does not fit closely within the record a groove. After a comparatively short distance of tracking, however, as illustrated by the position of the needle at 5', the wear of the bearing surface of the needle has been sufiicient to cause the same to accurately fit within the record groove. The final position of the needle is illustrated at 5 which position is nearest to the center hole of the record, and in which, as is clearly shown,

the depth of the groove has decreased to such an extent as to compensate for the wear of the needle, which still closely fits within the groove. The proportions of parts shown in the figures, and the slant of the bottom of the groove, are exaggerated and are merely illustrative. r a

The defect which my invention is designed to overcome is illustrated by Figs 2 and 3, in which a stylus or needle 5 is tracking a groove of uniform or slightly increasing depth in the record 1. The needle is shown in Fig. 2 as having advanced far enough along the record, so that an annular shoulder 8 is formed upon the needle, just above the upper surface of the record by the wearing away of the point of the needle. The needle is here represented as closely fitting within the record groove, the weight of the needle being borne by the shoulders 8,"

which have just been formed thereon. In Fig. 3 the same needle is repr sented at a later point in the reproduction f the record than that shown in Fig. 2, the weight of the needle is still supported by the shoulders 8,

but the-point and sides 'of the conical bearing surface 6 of the needle have been so worn by rubbing against the bottom and sides of the record groove 2*, as it,fits very loosely within the same, resulting in a, faulty reproduction.

It is obvious that if it were desired to have the record begin nearthe center hole 4 of the record disk and progress toward the periphery of the' disk, the groove nearest the center would be deepest and that nearest the periphery the most shallow.

I am aware that it has been proposed to compensate for the wear of the needle by forming a record groove of increasing width throughout the length thereof, but this is objectionable, because, tb cite one reason, a large number of grooves are commonly formed upon the record surface, and the urtherniore, increasing the width of a groove necessarily increases the depth as.

well, if the slant of the sides of the groove 7. is maintainedthe same, thereby; largely counter-acting the beneficial resultof widen desired character upon the masterrecord,.

ing the groove as a compensation for the latter progresses from the periphery of the record toward the center of the same, re-

wear of a conically pointed needle.

In Fig. 4 is illustrated one of many forms .of apparatus which may be employed in recording, to obtaiua record groove of the from which duplicate records are subsequen'tly made in well known-manner; As

there illustrated, the masterblank 1 is mounted for rotation, and is adapted to be fed toward the right, as shown by the "3,1": row, past the recording needle 9 by suitable and well known mechanism. The needle 9 is carried-by the lever 10 pivoted at 11 to v the sound box 12, the upper end of the lever being secured to the center of diaphragm13 in the soundbox. The sound box has a'neck 1.4; slidably mounted upon the end of a tube 15 having a cylindrical enlargement 16 mounted to oscillate in a vertical plane-upon trunnions 17, and within a cylindrical bearing 18. The latter carries a short neck 19 which is joined to the end-of the recording from 20 by a flexible coupling 21. The weight of the sound box tends to cause the same to oscillate about trunnions 17, and cause the recording needle to sink into the record blank when the latter is revolved. The depth of the cut at the beginning of. the record is regulated by a sliding weight 22 upon an arm 23 secured to the neck 15 as shown. The weight 22 may besecured at any desired point, on arm 23, beyond the pivot 17 to counterbalance the recorder and give the desired initial out. Also carried by arm 23 is a cup 24: above which is a receptacle 25, having a nozzle 26 of a bore or opening adjustable by screw 27 The receptacle 25 may be filled with fine sand, lycopodium powder, or other fine fiuid material either granular orliquid. When the ma-. 'chineis started, the valve 27 v is opened to the desired extent, and a line stream of material is allowed to flow uninterruptedly into cup 24 throughout the making of the record,-

This results in gradually and continually decreasing the pressure on the stylus as the sulting in the desired groove of continually decreasing depth. .eAs the granular material falls into cup 24in a'steady stream, there is no harmful vibration'imparted .to the recorder thereby. Obviously, other equivalent methods of obtaining the same result may be used, if desired.

\ Having now described my invention what I claim asnew and desire to protect by'Letters Patent is 1. As a new article of manufacture, a sound record having a continuous record groove of gradually decreasing depth 4 throughout its length, from. beginning to end, substantially as described.

2. 'As a new article of manufacture, a

sound record having a continuous record groove of the laterally undulating type, the depth of which decreases progressively and uniformly from the beginning to the end thereof, substantially as described. 3. As a new article of manufacture, a sound record having a continuous record groove of the laterally undulating type, the depth of which groove decreases from the beginning to the end thereof in such manner as approximately to compensate for the wear of a reproducing stylus or needle when the latter is tracking the same, substantiallyas described.

- This" specification signed and witnessed this 9th day of May, 1911.

DYER SMITH, HENRY SHELDON. 

